I would have suspected it would have been easier to just swap the entire shaft rather then try to inject the plastic into the holes again. Could explain how it still had the wrong bottom fitting, someone couldn't figure out how to get the old end off the shaft without messing with the injected plastic.

Any of them I have had apart have a groove on the inner shaft where the plastic is injected. Back in our dirt track days, we messed with a lot of steering shaft lengths, but because they were on the dirt track, as long as the shafts couldn't pull apart while the car was running around the track, we were not too concerned about the broken injected plastic. We made sure the columns had space to collapse, and couldn't be pulled apart under normal use, and raced on. If the crash was bad enough the column shafts could be pulled apart, the car was toast, and the column was the least of our concerns.

I had one column pull apart, the front frame rail was pulled away from the trans cross member about 6", I was driving the car, lost the steering, the brakes, and the trans bell (auto trans) at the same time. I got pinballed around and ended up stopped with the back end against the front straight wall. That was one really screwed up car! We stripped the good parts off what was left of that car and scrapped it, and moved on.